The present invention relates to a pressure reducing valve in which a secondary fluid pressure is set by actuating a cylindrical handle and a pressure gage is disposed in the handle (hereinafter referred to as "a gage-in-handle type pressure reducing valve").
Japanese Utility Model Registration Application Post-Examination No. 4-45043 discloses a gage-in-handle type pressure reducing valve in which a valve chamber is disposed between a primary-side port (supply port) and a secondary-side port (output port), and a main valve element (supply valve element) in the valve chamber is urged toward a main valve seat (supply valve seat) by a valve spring (return spring). The main valve element is also urged away from the main valve seat by a pressure regulating spring fitted between a feedback member (diaphragm) and a pressure regulating spring retainer. In addition, a pressure gage is disposed in a cylindrical handle, and a feedback chamber between the feedback member and the valve chamber communicates with the pressure gage through a pressure introducing communicating passage. The axial position of the pressure regulating spring retainer is adjusted with the handle.
In the above-described prior art, the pressure introducing communicating passage for introducing the pressure in the feedback chamber into the pressure gage comprises pressure introducing holes in a valve body wall and a bonnet wall and a passage in a pressure regulating screw. A considerably large number of man-hours is needed to form the pressure introducing holes in the valve body wall and the bonnet wall by machining. In addition, it is necessary to provide four O-rings in order to make the passage in the pressure regulating screw air-tight. Thus, the prior art is unfavorably complicated in structure and costly.